The public switched telephone network (PSTN) based on circuit switching technology has served well for the past several decades in making a broad range of telephony services possible for consumers and businesses. However, its infrastructure is fraught with cost inefficiencies, inflexible service creation and delivery platforms, and manually-intensive, error-prone operations, administration and maintenance (OA&M) applications and processes. All of these aspects combine to keep prices artificially high and make service creation and delivery intervals unduly long from an end-user perspective. In contrast, the broadband networking platforms that are being deployed for data services are optimized for high efficiencies and fast service creation due to the speed at which the market is driving the growth of new services. Given the large-scale investments in broadband network technologies being undertaken by the service providers to meet the explosive growth in demand, planning is underway to migrate voice services from the legacy circuit-switched environment to the newer broadband networking environment to take advantage of economies of scale. However, this migration needs to be carefully planned so it does not create a significant discontinuity in the features, services, and overall quality that customers have come to expect from the well-established circuit-switched network.
In the past, the typical home had a single telephone line for all the residents to share. Today, there has been a dramatic increase in the need for communication services in the home driven by such factors as telecommuting, home offices, residential facsimile machines and computer networking including Internet access.
In the traditional PSTN environment, each telephone circuit, called a “loop”, requires a separate wire pair from the access service provider's facilities to the subscriber's location. This places practical limits on the number of circuits that may be available at each subscriber location, especially for residential subscribers. The access service provider generally does not have sufficient capacity in the loop facilities to provide multiple telephone lines to every subscriber.
Furthermore, most homes have been wired for one or at most two telephone lines. Adding a new telephone line beyond this usually requires adding new wiring in the home. This home wiring limit acts as a barrier to residential users who may want additional telephone lines and to service providers who would like to gain additional revenues from providing new communication services.